A novel performance tradeoff in heterogeneous networks : a multi-objective approach

In this letter, we investigate the performance tradeoff between different tiers of heterogeneous networks (HetNets) consisting of a macrocell as the basic tier and small cells (e.g., picocells, femtocells, etc.) as the other tiers. Due to the interference among tiers in the HetNets, the performance of different cells are interactive. Maximizing the total performance in terms of data rate and energy efficiency (EE) of users in HetNets are both desirable system design objectives, however, it is expected that there is a non-trivial tradeoff between tiers due to the co-channel deployment. Thus, we formulate our resource allocation problem as a multiobjective optimization problem (MOOP) in which the performance of the macrocell and small cells are jointly maximized. Using the weighted Tchebycheff technique, we are able to transform the MOOP into a single objective optimization problem (SOOP). Then, an iterative algorithm is proposed to solve this SOOP which yields a locally optimal solution. Finally, our numerical results show this tradeoff among different tiers